(1 北京市建筑设计研究院 100045；2 五洲工程设计研究院 北京 100053)
［提要］ 全国农业展览馆新建中西广场展厅平面为1505m×91m矩形，高度160m，主体为钢筋混凝土框架，上部钢屋盖为77m跨张弦桁架结构。对屋盖设计中的几种可行结构方案进行了比较，对张弦桁架整体控制尺寸的确定进行了研究。介绍了屋盖的结构平面布置，张弦桁架的受力分析及设计，撑杆上下端及支座等较为复杂的节点设计。索穿下弦杆及索端头锚固处等受力较复杂的节点采用了铸钢节点，进行了两类铸钢节点设计与受力分析。并对屋架的施工过程进行了简要介绍。
［关键词］ 全国农展馆 展厅 张弦桁架 预张力 铸钢节点
Design and Analysis of Prestressed Truss String Roof Structure in the Exhibition Hall on Midwest Square for China International Agriculture Exhibition Center/Wei Dong1，Wang Zhigang1，Liu Jikang1，Ding Dayi2(1 Beijing Institute of Architectural Design & Research,Beijing 100045,China; 2 Wuzhou Engineering & Research Institute,Beijing 100053,China)
Abstract:The new Midwest Exhibition Hall for China International Agriculture Exhibition  Center is sized of 1505m×91m with 160m heigh.The main structure system is of reinforced concrete frame.The steel roof structure is 77mspan prestressed truss string structure(PTSS).The feasible roof structural styles are compared and how to choose the control sizes of PTSS are explained in detail.The roof structural layout,the design and calculation method of PTSS are introduced comprehensively.The detail of casting steel joint and slidinghinge connection are presented.The design and calculation of two types of casting steel connections are introduced in detail.And the steel roof construction process are mentioned compactly.
Keywords:prestressed truss string structure;prestress;casting steel connection